The present invention relates to a non-contaminating paint strainer constructed of paperboard material and its blank wherein the mesh screen is glued to the outer surface of the strainer, whereby paint being filtered by the receptacle will be in contact solely with the inner surface of the strainer, which is free of glue and printed matter.
In our U.S. Pat. No. 4,559,140, we describe a paint strainer having a reinforced lower filtration aperture. Often, when filtering liquids, such as paint, lumps of paint will lodge themselves against the inner surface of the strainer and cause obstruction to the filtration aperture. Also, the paint strainer can be used for substantially long periods of time when filtering paint from a large can, and this places the paint in contact with the inner surface of the filter and the screen. We have recently discovered that such strainers can contaminate the paints or solvents being filtered, as the glue that is used to glue the screen to the filter, or glue parts of the filter structure, does soften and dissolve into the paint when exposed thereto. This can cause serious problems, depending on the quality and use of such paints or solvents.
Another problem with paint strainers is that many of these are formed of paperboard material and often there is printed material on the inner surface of the filters. The ink pigments also dissolve within the paint and cause contamination.
It is therefore a feature of the present invention to provide a non-contaminating paint strainer and its blank and which substantially overcomes the above-mentioned disadvantages of the prior art.
It is a further feature of the present invention to provide a non-contaminating paint strainer wherein the filtration mesh screen is glued to the outer surface of the strainer by a water-base glue.
Another feature of the present invention is to provide a non-contaminating paint strainer wherein any printed material is contained solely on the outer surface of the strainer and wherein the inner surface of the strainer is free of any contaminating substances.
Another feature of the invention is to provide a reinforced rib in the filtration extending to the apex of the cone.
Another feature of the present invention is to provide a paint strainer blank having the above-noted features.
According to the above features, from a broad aspect, the present invention provides a non-contaminating paint strainer which comprises a conical receptacle having a conically tapering side wall. The side wall has an inner surface and an outer surface. The conical receptacle defines an upper support portion having an open end and a lower conical filtration portion. The lower conical filtration portion has an aperture. Rib reinforcing means are formed integral with the side wall and extend into the aperture. A filtration mesh screen surrounds the aperture and is secured to the outer surface of the tapering side wall adjacent the aperture and to an outer surface of the rib reinforcing means by e water-base glue applied solely to the outer surface of the side wall and outer surface of the rib reinforcing means, whereby paint being filtered by the conical receptacle will be in contact solely with the inner surface, which is free of said glue. The rib reinforcing means provides stress distribution and rigidity to the screen in the aperture, and defines a lower conical support for the screen from a top edge of the aperture to a conical tip thereof defined by the rib reinforcing means. The lower conical support defines an apex for the receptacle and provides minimum obstruction to prevent accumulation of paint and obstruction to the mesh screen.
According to a still further broad aspect of the present invention, there is provided a non-contaminating paint strainer blank, which comprises a flat sheet having an inner surface and an outer surface. The flat sheet has opposed side edges and opposed symmetrical end edges and configured to be folded into a conical-shaped strainer. A first one of the side edges has a substantially convex shape in a major central portion thereof. A second one of the side edges is of substantially concave shape in an aligned major central portion. A V-shape cut-out is centrally disposed in the second side edge. A small pointed arm protrudes into the V-shape cut-out adjacent the concave side edge and terminates at its apex on the central transverse axis of the blank. Two large symmetrical apertures are cut out on a respective side of the V-shape cut-out opening and spaced inwardly of the concave side edge and a one-piece filtration mesh screen is glued to the outer surface of the blank by a water-base glue and overlies the two large apertures and a substantial portion of the V-shape cut-out opening.